While the U.S.'s core strength has always been propaganda (they got Operation Paperclip Nazis to becom American patriots, got the USSR to abolish itself, and the young Russian Federation to destroy itself with its infamous "shock therapy"), China also has quite strong propaganda, especially in Africa. And in Europe, go back 30 years and people still saw Americans as liberators; now, Europeans see it as a corrupt third-world country where people can't afford healthcare.

And while it's true that U.S. cultural "force projection" hasn't weakened; they are being severely squeezed when it comes to trade dominance (https://merchantmachine.co.uk/china-vs-us/) and monetary dominance (see James Rickards' books).

America still has its hegemony, but the notion that it's declining is very much mainstream in academia (https://www.routledge.com/Americas-Allies-and-the-Decline-of...). Worse, its national security institutions have lost credibility among a significant portion of its electorate (MAGA people), and its military hegemony is now opposed by both populist left (pacifists) and populist right (non-interventionists). They're being squeezed both abroad and at home.